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Bacillus cereus is a food pathogen of major concern to the dairy industry. Strains of B. cereus were isolated in 2006 and 2010 from a pasteurized milk processing line in a dairy plant in Algeria. Pasteurized milk is obtained from reconstituted and processed milk powder. This study was designed to discriminate between the isolated B. cereus strains and to predict their food poisoning potential. Strains were fingerprinted by M13-PCR, and identified at the phylogenetic group level by amplified panC gene sequence analysis. They were clustered into three distinct M13-PCR groups: one major group which included 17 strains and two minor groups which contained two and one strains, respectively. Strains originating from both the process equipment and milk powder were from the major group indicating that milk powder was the main source of initial contamination. Strains from the major and second group were affiliated to the mesophilic phylogenetic group III while the unique strain of the third group was classified into the mesophilic phylogenetic group IV. The data presented in this study showed a very low genetic diversity among B. cereus strains identified in milk powder and secondly by milk processing systems, as well as persistence in the dairy environment of specific B. cereus genotypes, across 4 years. M13-PCR typing and phylogenetic affiliation were useful for characterizing B. cereus dairy isolates, permitting their differentiation within the B. cereus group, and showing homogeneous contamination throughout the pasteurized milk processing line. The recurrent genotypes which belong to the potentially toxigenic group III B. cereus could threaten pasteurized milk safety. [ABSTRACT FROM AUTHOR]

Abstract: Gergoush is a naturally fermented Sudanese Bread snack produced in three fermentation steps (primary starter, adapted starter and final dough), followed by three baking steps for a half to one hour at above 200°C. This study examines the microbiota of two sets of fermentations performed at a traditional production site in Khartoum, Sudan in 2006 and 2009, respectively. In 2006 four different milk/legume based primary starters (faba bean, chick pea, lentil and white bean) were sampled in order to enumerate and identify the Bacillus at species or group level. In 2009 specific focus was on the enumeration and safety evaluation of the dominant Bacillus cereus group species occurring during various Gergoush productions (including the three fermentations steps and after baking). In 2006, the primary starters contained Bacillus spp. in the order of between 7.7 and 8.1log10 CFU/g. Species identifications were performed by M13-PCR typing using the Escherichia coli phage M13 derived primer PM13 combined with internally transcribed 16–23S rRNA PCR, 16S rRNA gene and gyrA or gyrB gene sequencing, and selected phenotypic tests. Depending on the legume used, 40–68% of the isolates were identified as B. cereus sensu lato, 16–27% as Bacillus licheniformis, 8–32% as Bacillus subtilis and 4–20% as Bacillus sonorensis. During the second set of fermentation trials performed in 2009, the Bacillus spp. and B. cereus occurred in numbers of between 7.7–9.9 and 6.1–7.8log10 CFU/g, respectively, while no bacteria were detected after baking. A total of 180 B. cereus sensu lato isolates from four different primary starters, adapted starters and final doughs were further identified as B. cereus sensu stricto (118 isolates) and Bacillus thuringiensis (62 isolates). The safety of Gergoush was evaluated based on the counts and toxin gene profiles of the dominant B. cereus species. Considering that no bacteria survived the baking process, and that the cereulide synthetase gene cesB involved in the production of the heat stable emetic toxin cereulide was not detected in any of the investigated B. cereus isolates, the results indicate, that Gergoush produced at the traditional production site is safe for human consumption. This study is the first to identify the Bacillus of Gergoush to species level, and it is the first to perform a safety evaluation of the product, based on the dominant B. cereus species. [Copyright &y& Elsevier]